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Ford Focus Service Manual: Air Conditioning (A_C) Odor Treatment

Ford Focus Service Manual / HVAC / Cooling / Air Conditioning (A_C) Odor Treatment

Special Tool(s)

Flexible Applicator Tool 258-00005

Item Specification
Motorcraft® A/C Cooling Coil Coating YN-29

out this procedure in a well-ventilated area with all vehicle windows and doors opened. Carefully read cautionary information on product label. For EMERGENCY MEDICAL INFORMATION, seek medical advice. On Ford/Motorcraft products in the USA or Canada call: 1-800-959-3673. For additional information, consult the product Material Safety Data Sheet (MSDS), if available. Failure to follow these instructions may result in serious personal injury.


There are typically 4 types of objectionable odors found in a vehicle:

Before determining that A/C odor treatment is required, the source and the circumstances under which the odor occurs must be determined.


Chemical odors are usually constant regardless of the climate control system setting although they may be enhanced by A/C operation. Most chemical odors are caused by fluid leaks or incorrectly cured adhesives. Chemical odors can be eliminated by repairing the leaking component and removing any residue.


Environmental odors usually occur for a short time and diminish after the vehicle passes through the affected area. These odors are typically only detected when the vehicle windows are open, or when the climate control system is operating in a mode that allows for fresh air. Environmental odors cannot be eliminated because they are external in source, but they may be minimized by switching to a climate control setting that uses recirculated air.


Human and other interior-generated odors occur while the source is present and may linger for a short time after. These odors may be more noticeable during A/C operation. Human odors may be eliminated by removing the source and cleaning the affected area.


Microbiological odors, if in the A/C system, usually last for about 30 seconds after the system is turned on. They will be detected while the A/C is turned on and using either outside or recirculated air. Microbiological odors that occur in areas other than the A/C system (for example, water in doors or wet carpeting) may last indefinitely and will be more intense when recirculated air is used. Microbiological odors will not be present at temperatures at or below 10°C (50°F).

Microbiological odors can be eliminated by removing the source and treating the affected area. Standing water must be allowed to drain and dry out. A/C systems may be treated by using A/C cooling coil coating as described in the service procedure below.

Microbiological odors result from microbial growth supported by warm temperatures and moisture. Microbiological odors are described as musty/mildew type smells and may occur on/in:
  1. Identify the type of odor present in the vehicle. Do not proceed with A/C odor treatment if the odor source is found to be outside of the A/C system. Refer to the following chart for examples.

    Odor Source Odor Description
    Chemical Odors

    Coolant Sweet smell
    Fuel Gasoline or diesel fuel smell
    Oil Oil type or burning smell
    Power Steering Fluid Oil type or burning smell
    Transmission Fluid Oil type or burning smell
    Washer Fluid Alcohol type smell
    Gear Lube Garlic/sulfur smell
    Refrigerant Oil Ether type smell
    Carpet/trim Adhesives Fishy, urine or sweet smell
    Evaporator Core Coating Wet cement type smell
    Environmental Odors

    Exhaust Exhaust, fuel or burning type smell
    Industrial Pollutants Various smells
    Dust Musty, mildew or wet cement type smell
    Pollen Sweet smell
    Tobacco Burning, tar smell
    Human and Other Interior Generated Odors

    Body Secretions Body odor
    Perfuming Agents Sweet or fragrance smell
    Clothing Musty, mildew or body odors
    Food/Beverage Sweet, musty, mildew or fishy smell
    Microbiological Odors

    Microbiological Odors Occurring Inside of A/C System Musty, mildew smell lasting about 30 seconds after A/C is turned on
    Microbiological Odors Occurring Outside of A/C System Musty, mildew smell lasting indefinitely and possibly more pronounced when using recirculated air

  1. Identify the source of the odor.
    • Check the evaporator core drain tube for restriction.
    • Check the passenger and driver side carpet for moisture. If moisture is found, A/C odor treatment is not necessary. Diagnose for a water leak as needed.
    • Check the blower motor and blower motor cover (if equipped) for moisture resulting from water bypassing the cowl baffling system. If moisture is found, A/C odor treatment is not necessary. Diagnose for a water leak as needed.
    • Check the cowl top panel and air inlet screen for standing water or foreign material. If possible, remove any standing water and clean the air inlet screen using a wet/dry vacuum.
  1. Open all vehicle windows and doors.
  1. Make sure that the A/C is off.
  1. Set the following.
    • Select PANEL mode (A/C off).
    • Adjust the temperature setting to full warm.
    • Adjust the blower motor speed to HI.
  1. Run the engine for 25 minutes to dry out the A/C system.
  1. Turn the ignition OFF.
  1. Remove the blower motor.
  1. NOTE:

    Blower motor speed controls that are mounted outside of the evaporator core housing and not exposed to the blower motor airflow do not need to be removed.

    Remove the blower motor resistor (if equipped) or blower motor speed control (if equipped and exposed to the inside of the evaporator core housing).

  1. NOTICE: To avoid damage to the vehicle interior, do not spill or spray this product on any interior surface.

    Add one full bottle of A/C cooling coil coating to the Flexible Applicator Tool.

  1. Insert the nozzle into the evaporator housing and direct the spray toward the evaporator core face. Spray the entire evaporator core face until empty.
  1. Install the blower motor and blower motor resistor (if equipped) or blower motor speed control (if equipped).
  1. Repeat Steps 4 through 6 to cure the evaporator core coating.

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